ENGINE PERFORMANCE
For every task in Engine Performance the following safety requirement must be strictly
enforced:
Comply with personal and environmental safety practices associated with clothing; eye
protection; hand tools; power equipment; proper ventilation; and the handling, storage, and
disposal of chemicals/materials in accordance with local, state, and federal safety and
environmental regulations.
A. General: Engine Diagnosis
Priority Completed
1. Identify and interpret engine performance concerns;
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determine necessary action.
2. Research applicable vehicle and service information,
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vehicle service history, service precautions, and technical
service bulletins.
3. Diagnose abnormal engine noises or vibration concerns;
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determine necessary action.
4. Diagnose the cause of excessive oil comsumption, coolant
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comsumpton, unusual exhaust color, odor, and sound;
determine necessary action.
5. Perform engine absolute (vacuum/boost) manifold pressure P-1
tests; determine necessary action.
6. Perform cylinder power balance test; determine necessary
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action.
7. Perform cylinder cranking and running compression tests;
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determine necessary action.
8. Perform cylinder leakage test; determine necessary action.
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9. Diagnose engine mechanical, electrical, electronic, fuel,
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and ignition concerns; determine necessary action.
10. Verify engine operating temperature; determine necessary
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action.
11. Verify correct camshaft timing.
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B. Computerized Controls Diagnosis and Repair
1. Retrieve and record diagnostic trouble codes, OBD monitor P-1
status, and freeze frame data; clear codes when applicable.
2. Access and use service information to perform step-by-step P-1
(troubleshooting) diagnosis.
3. Perform active tests of actuators using a scan tool;
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determine necessary action.
4. Describe the importance of running all OBDII monitors for
repair verification.
5. Diagnose the causes of emissions or driveability concerns
with stored or active diagnostic trouble codes; obtain, graph
and interpret scan tool data.
6. Diagnose emissions or driveability concerns without stored
diagnostic trouble codes; determine necessary action.
7. Inspect and test computerized engine control system
sensors, powertrain/engine control module (PCM/ECM),
actuators, and circuits using a graphing multimeter
(GMM)/digital storage oscilloscope (DSO); perform
necessary action.
8. Diagnose driveability and emissions problems resulting
from malfunctions of interrelated systems (cruise control,
security alarms, suspension controls, traction controls, A/C,
automatic transmissions, non-OEM installed accessories, or
similar systems); determine necessary action.
C. Ignition System Diagnosis and Repair
1. Diagnose (troubleshoot) ignition system related problems
such as no-starting, hard starting, engine misfire, poor
driveability, spark knock, power loss, poor mileage, and
emissions concerns; determine necessary action.
2. Inspect and test crankshaft and camshaft position sensor(s);
perform necessary action.
3. Inspect, test, and/or replace ignition control module,
powertrain/engine control module; reprogram as necessary.
4. Remove and replace spark plugs; inspect secondary ignition
components for wear and damage.
D. Fuel, Air Induction, and Exhaust Systems Diagnosis and
Repair
1. Diagnose (troubleshoot) hot or cold no-starting, hard
starting, poor driveability, incorrect idle speed, poor idle,
flooding, hesitation, surging, engine misfire, power loss,
stalling, poor mileage, dieseling, and emissions problems;
determine necessary action.
2. Check for fuel contaminants; determine necessary action.
3. Inspect and test fuel pumps and pump control systems for
pressure, regulation, and volume; perform necessary action.
4. Replace fuel filter(s).
5. Inspect, service, or replace air filters, filter housings, and
intake duct work.
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6. Inspect throttle body, air induction system, intake manifold
and gaskets for vacuum leaks and/or unmetered air.
7. Inspect and test fuel injectors.
8. Verify idle control operation.
9. Inspect integrity of the exhaust manifold, exhaust pipes,
muffler(s), catalytic converter(s), resonantor(s), tail pipe(s),
and heat shields; perform necessary action.
10. Inspect condition of exhaust system hangers, brackets,
clamps and heat shields; repair or replace as needed.
11. Perform exhaust system back-pressure test; determine
necessary action.
12. Check and refill diesel exhaust fluid (DEF).
13. Test the operation of turbocharger/supercharger systems;
determine necessary action.
E. Emissions Control Systems Diagnosis and Repair
1. Diagnose oil leaks, emissions, and driveability concerns cause
by the positive crankcase ventilation (PCV) system; determine
necessary action.
2. Inspect, test, and service positive crankcase ventilation (PCV)
filter/breather cap, valve, tubes, orifices, and hoses; perform
necessary action.
3. Diagnose emissions and driveability concerns caused by the
exhaust gas recirculation (EGR) system; determine necessary
action.
4. Diagnose emissions and driveability concerns caused by the
secondary air injection and catalytic converter systems;
determine necessary action.
5. Diagnose emissions and driveability concerns caused by the
evaporative emissions control system; determine necessary
action.
6. Inspect and test electrical/electronic sensors, controls, and
wiring of exhaust gas recirculation (EGR) systems; perform
necessary action.
7. Inspect, test, service, and replace components of the EGR
system including tubing, exhaust passages, vacuum/pressure
controls, filters, and hoses; perform necessary action.
8. Inspect and test electrical/electronically-operated components
and circuits of air injection systems; perform necessary action.
9. Inspect and test catalytic converter efficiency.
10. Inspect and test components of hoses of the evaporative
emissions control system; perform necessary action.
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11. Interpret diagnostic trouble codes (DTCs) and scan tool data
related to the emissions control systems; determine necessary
action.
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